Comparison of additive manufacturing technologies for injection molding

Abstract

The objective of this project is to determine which Additive Manufacturing family between Material Jetting (Polyjet technology) and Vat Photopolymerisation (Stereolithography -SLAtechnology) is the best for the creation of injection molds for the plastic injection process. The comparison was made by analyzing the technological parameters of each technology and the post-injection results regarding the mold and injected parts. The injection process was carried out in the Department of Mechanical Engineering and Materials of TECNUN using the MTT 100 KSA injection molding machine. Specifically, the impression material of each technology (Rigid 10K for SLA and Digital Plus ABS for Polyjet) was compared using heat and tensile tests to analyze the thermal conductivity of each mold. On the other hand, the injected parts were analyzed using a roughness meter and the HandyScan 300 scanner along with the VXinspect software to measure the dimensional and geometric tolerances. It was concluded that Polyjet technology is better for the production of injection molds since with this technology more durable and smooth molds were obtained in less time. Precisely, the results showed that Polyjet technology has a better print quality, and an exceptional surface finish is obtained both in the parts and in the mold. As this technology does not require post-processing processes, it is faster in terms of production. Plus, the printing material ABS Digital Plus does not crack with heat like the mold printed with Rigid 10K for SLA. However, if high precision and tight tolerances are crucial, SLA technology is preferred, as long as production speed and mold durability are not critical parameters.